Ancient shipwrecks are mysterious, remote, other-worldly; they captivate our imagination. Most people believe that shipwrecks are rare. Actually they are nearly as commonplace as car accidents, but there are no tow trucks to clear away debris on the sea floor. Over thousands of years of Mediterranean seafaring, hundreds of thousands of vessels and sailors met their end in wrecking events. Instead of valuable treasure, most ancient ships carried the mundane commodities of long-distance trade. Many of these wrecks are composed of now-empty amphoras that once contained bulk goods such as wine and olive oil. The trick for maritime archaeologists is to extract meaningful conclusions about our early ancestors based on these shipwrecks, the partial remains of ancient trade. Until recently, that meant months or years of scuba diving on a small number of wrecks to map their features and excavate their artifacts.

A long-term partnership between the Hellenic Ministry of Culture Ephorate of Underwater Antiquities (EUA) and the Woods Hole Oceanographic Institution (WHOI) delivers a fresh approach to underwater archaeology. Conceived in 2004 by Ephorate Director Katerina Dellaporta and carried on by her successor, Calliope Preka-Alexandri, this international collaboration applies advanced technologies to map and completely photograph each wreck in a single afternoon. The goal is to survey hundreds of wrecks rapidly without disturbing the sites, and so build a statistically valid database of comparable wrecks from all time periods. The productivity of this new strategy is readily apparent. In just three field seasons, our interdisciplinary group of archaeologists, scientists, and engineers has investigated fifteen shipwrecks.1

The team deploys Greek and American technology. On some projects, the Hellenic Centre for Marine Research has contributed the Greek national research vessel Aegaeo and dives in the Thetis manned submersible, capable of depths to 600 meters. WHOI's underwater robots extend archaeologists' reach even deeper: to the Mediterranean's abyssal sea floor at 5000 meters. In the first trials of a free-swimming Autonomous Underwater Vehicle (AUV) for archaeology, the team in 2005 surveyed a 4th century BC wreck between the islands of Chios and Oinousses. We spent just 24 hours at the site, while the unmanned AUV robot performed four missions and collected more than 7000 high-resolution digital images of the shipwreck. The AUV also mapped the wreck with sonar and "smelled" it with chemical sensors. The result was a series of very precise maps showing the artifacts' locations in three dimensions, and the chemical profile of the water around the wreck.

These data answered the archaeologists' most important questions about the wreck: its date, vessel size, origin and composition of the cargo, volume of cargo, and clues to its state of preservation. The digital images showed that the top layer of cargo held more than 350 amphoras of two types, one from Chios and the other of unknown provenance. The Chian jars' style indicated a sinking date of about 330 B.C. +/-20 years. The sonar data gave the vessel's size: 21 m x 8 m, with the amphora mound standing 1.4 m high.2 On other Classical wrecks, excavation has shown that 1.4 m is enough to hold four or five tiers of amphoras. The wrecked vessel off Chios almost certainly carried more than 1,000 amphoras.

The amphoras discovered on shipwrecks are almost always empty, their stoppers unglued soon after sinking. Until now, identifying the original contents of empty amphoras has been impossible, leaving archaeologists to assume much before drawing necessarily tentative conclusions. By applying a bit of scientific magic, this problem has been solved. A molecular biologist from Lund University, Sweden, joined the Greek and American researchers to develop a new analytical technique. Under her direction, EUA archaeologists collected minute ceramic samples from the insides of empty amphoras recovered from the Chios-Oinousses wreck. From these subtle scrapings, remnant ancient DNA can be extracted, providing precise and accurate information about ancient industry and trade.

The first trial of this method delivered surprising results. Chian amphoras usually are described as wine jars, in deference to ancient texts extolling the island's distinctive vintages. Instead of grape DNA, the amphora from the wreck contained the DNA of olive and oregano.3 The herbal additive would have flavored and helped preserve the olive product, possibly oil. With the direct evidence provided by DNA, archaeologists can for the first time begin to reconstruct accurately agricultural output, production of value-added goods, and preparation and preservation of food and commodities. Remnant DNA can be extracted from artifacts that appear to be completely empty. This opens previously unimagined research vistas for the thousands of amphoras stored in Ministry of Culture warehouses, university study collections, and museums around the world.4

The techniques pioneered through this international partnership were originally intended for deep submergence surveys, but they can also be applied to diving archaeology. To showcase this, in 2008 the team performed scuba operations around the north coasts of Chios and Oinousses. Working with a list of shipwrecks reported to the Ephorate of Underwater Antiquities, the team photodocumented ten ancient wrecks in ten days. The wrecks range in date from the 7th century B.C. to the 5th century A.D. This is the greatest concentration of ancient shipwrecks ever investigated. Unlike deep water wrecks, many of these shallow sites are badly disturbed by wave action and centuries of human interference. Nonetheless, useful archaeological information can be extracted quickly and efficiently from individual digital images and composite photomosaics. Samples of amphora sherds from each wreck are now undergoing ancient DNA analysis to reveal cargo contents. By comparing the Chios and Oinousses shipwrecks and their cargoes, long-term patterns of trade will emerge.

Greek waters hold thousands of ancient shipwrecks, and in the greater Mediterranean region they are countless. The Hellenic Ministry of Culture and Woods Hole Oceanographic Institution's very fruitful scientific partnership and advanced methods will continue, and can be emulated elsewhere. With archaeologists able to investigate more sites than previously imaginable, the origins of civilization will emerge from the depths of time and sea.

The author thanks colleagues Katerina Dellaporta and Calliopi Preka-Alexandri, Hellenic Ministry of Culture; Dimitris Kourkoumelis and Theotokis Theodhoulou, Ephorate of Underwater Antiquities; and Maria Hansson, Lund University. This research program is funded by National Science Foundation Office of International Science and Engineering grant no. OISE-0923229 and NSF Censsis Engineering Research Center grant no. EEC9986821; National Oceanic and Atmospheric Administration Office of Ocean Exploration and Research grant no. NA06OAR4600092, no. NA09OAR4600083 and NOAA grant no. EA133C05SE5157; United States Department of State; Woods Hole Oceanographic Institution Wheeler Award for Ocean Science and Society and WHOI Mary Sears Visitor Program; Hellenic Ministry of Culture, Hellenic Centre for Marine Research, and Prefecture of Chios; Lund University and Royal Physiographic Society, Sweden; and private sponsors including Susan and Robert Bishop, Jane and James Orr, Cathy and George Sakellaris, Joseph Patton, and others.